Texas Instruments LP2985IM5-3.6

Overview

LP2985IM5-3.6 from Texas Instruments is a micropower, ultra-low-dropout linear regulator delivering 150 mA output current with 3.6 V fixed output voltage, 300 mV typical dropout at full load, 1% output accuracy (A-grade), and <1 µA shutdown quiescent current. It operates from 2.5 V to 16 V input and targets battery-powered portable electronics requiring low noise and high efficiency under tight voltage headroom.

For engineers reviewing the LP2985IM5-3.6 datasheet, LP2985IM5-3.6 pinout, LP2985IM5-3.6 application, or LP2985IM5-3.6 equivalent, key selection criteria include verified 5 mΩ minimum ESR stability with ceramic capacitors, 30 µV_RMS noise performance with 10 nF BYPASS capacitor, ON/OFF logic control interface, and SOT-23-5 thermal derating behavior in compact PCB layouts.

Technical Context

The LP2985IM5-3.6 uses a vertically integrated PNP (VIP) pass transistor architecture enabling ultra-low dropout (280–575 mV at 150 mA over temperature) and low ground current (850 µA typical at 150 mA). Its internal reference and error amplifier deliver 1% initial output tolerance and ±3.5% total variation across –40°C to 125°C junction temperature.

It integrates active ON/OFF control with 1.6 V enable threshold and 0.15 V disable threshold, foldback current limiting (400 mA short-circuit, 350 mA peak), and thermal shutdown protection. Stability is ensured with ceramic output capacitors ≥2.2 µF and ESR as low as 5 mΩ - no external compensation required.

Key Specifications

Pinout & Package

LP2985IM5-3.6 is housed in a standard 5-pin SOT-23 package (2.90 mm × 1.60 mm body), optimized for space-constrained portable designs and compatible with automated pick-and-place assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise, micropower LDO applications.

Compared with TLC7603-36 and MCP1703T-3602E/MB, the LP2985IM5-3.6 uniquely combines 150 mA capability, sub-1 µA shutdown, 30 µV_RMS noise via BYPASS, and ON/OFF control in a single SOT-23-5 device - making it optimal for battery-constrained, noise-sensitive, and duty-cycled applications.

Availability

LP2985IM5-3.6 is available at Aetrix Electronics and suitable for cellular phones, portable medical sensors, laptop subsystems, and digital camera image sensor biasing requiring stable component supply, long-lifecycle support, and guaranteed traceability.

Supply support for LP2985IM5-3.6 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in power management IC design.

The LP2985-N product line was engineered specifically for micropower, ultra-low-noise, ultra-low-dropout regulation in space- and battery-constrained portable electronics - emphasizing precision, efficiency, and robustness across automotive and industrial temperature ranges.

FAQ

What is the minimum input voltage required for LP2985IM5-3.6 to regulate 3.6 V at 150 mA?

The LP2985IM5-3.6 requires a minimum input voltage of 4.175 V at 150 mA under worst-case conditions (125°C junction temperature), based on its maximum dropout voltage of 575 mV. At room temperature, typical dropout is 280 mV, allowing regulation from as low as 3.88 V. Input must remain ≥2.5 V for basic functionality, but regulation is not guaranteed below V_OUT + V_DO(max).

Does LP2985IM5-3.6 require an external bypass capacitor to achieve its specified 30 µV_RMS noise performance?

Yes. The LP2985IM5-3.6 achieves 30 µV_RMS output noise (300 Hz–50 kHz) only when a 10 nF ceramic capacitor is connected between the BYPASS pin and GND. Without this capacitor, output noise rises significantly - the BYPASS pin directly shunts reference noise, and omitting it degrades noise performance by >2×. The capacitor must be low-leakage ceramic or film type.

Can LP2985IM5-3.6 operate with a 1 µF output capacitor instead of the recommended 2.2 µF?

No. The LP2985IM5-3.6 requires a minimum 2.2 µF ceramic output capacitor for guaranteed stability across all load and temperature conditions. Using only 1 µF risks oscillation or poor transient response, especially at higher loads or elevated temperatures. The datasheet explicitly specifies 2.2 µF as the minimum; increasing capacitance is allowed and improves load-step immunity.

What is the maximum allowable power dissipation for LP2985IM5-3.6 in the SOT-23-5 package?

The LP2985IM5-3.6 has a junction-to-ambient thermal resistance (R_θJA) of 169.0°C/W in a standard PCB layout. With a maximum junction temperature of 125°C and ambient temperature of 85°C, the maximum allowable power dissipation is approximately 237 mW. Exceeding this causes thermal shutdown. At 150 mA and 575 mV dropout, dissipation is 86 mW - well within safe limits under typical conditions.

Is LP2985IM5-3.6 pin-compatible with other members of the LP2985-N family, such as LP2985IM5-3.3 or LP2985IM5-5.0?

Yes. All LP2985-N variants in the SOT-23-5 (DBV) package share identical pinout, footprint, and thermal characteristics. The only differences are fixed output voltage and minor electrical tolerances (e.g., 3.3 V vs. 3.6 V vs. 5.0 V). This allows direct substitution in existing layouts when voltage requirements change - provided input headroom and load current remain within specification for the new variant.